On Cellular capable iPads, it’s still a normal GPS chip plus antenna, independent of the 3G/4G/5G network.
If you have no mobile signal, it may take slightly longer (up to 1 minute) to acquire an initial fix, rather than a few seconds. This is because normally the mobile internet allows the iPad to rapidly download the GPS the almanac (rather than over the GPS signal itself), allowing it to get a faster initial fix.